Transfusion of blood and blood plasma is now one of the most effective means for treating major hemorrhages resulting from burns and states of shock and other causes. Under extraordinary conditions, such as in wars or major disasters, transfusions are very often carried out with considerable difficulty, particularly in regard to the availability of sufficient quantities of blood or of blood of individual groups. Restricted preservation time, sensitivity to noxious factors, as well as exacting conditions of transport and storage make large stockpiles almost impossible. Further, inconveniences arise from the necessity of blood group determination and cross tests. All of these inconveniences were apparent as early as prior to and during World War I. However, at that time all efforts to find suitable blood plasma substitutes such as those containing gum arabic or gelatin were not successful.
In 1878 it was known that physiological solutions were suitable as substitutes for blood in the treatment of hemorrhages. However, they were of limited use until the fundamental difference between crystalloids and blood and blood plasma were discovered and it was established that the therapeutic effect of these physiological solutions depends mainly on the colloid-osmotic properties thereof. It was also established that for bed patients the most important thing is to replace the lost volume of blood and not the lost erythrocytes. The influence of this knowledge appeared in further work concerning the discovery of better blood plasma substitutes having better colloid-osmotic properties than the then known physiological solutions had. As a result many plasma substitutes were suggested but few proved applicable.
It is therefore, a primary object of the invention to provide new blood plasma substitutes having good colloid-osmotic properties and comprising physiological solutions of polymers or copolymers on monoesters of acrylic and/or methacrylic acid either with aliphatic polyols having at least two hydroxylic groups and one etheric group, or at least three hydroxylic groups, or consisting of N-mono-or di-substituted or non-substituted amides of said acids, the substituents being either lower alkyls with 1-4 carbon atoms, or hydroxyalkyl groups with one or more hydroxylic groups and containing 1-6 carbon atoms and wherein, if desired, the copolymers may contain a minor amount of other monomer units such as ethylene glycol monoethacrylate, methyl methacrylate and the like in an amount which does not affect the water-solubility of the copolymer or wherein various of the monomers may be also mutually copolymerized.
Another object of the invention is a method of manufacturing blood plasma substitutes consisting in carrying out the polymerization or copolymerization in a solution, preferably, in an aqueous solution, although other known polymerization solvents can be used and then precipitating the polymer out of the solution thus obtained by pouring it into an excess of a non-solvent for the polymer or copolymer, the non-solvent being miscible with the primary solvent in which the polymerization or copolymerization takes place and subsequently dissolving the precipitate in a physiological solution.